1. Field of the Invention
The present invention relates to an image input device, and more particularly to transmission illumination necessary for inputting an image of a transmission original.
2. Related Background Art
In the following specification, an image input device will be described taking as an example a so-called electronic over-head projector, conventionally known in the art, capable of reproducing an image of an original placed on an original pedestal and taken with a video camera to display it on a monitor, or project it on a screen using a projector.
A conventional image input device is constituted by, as shown in FIG. 10, an original pedestal 51 on which an original is placed, a camera 53 having a photoelectric conversion unit for reading an original, and a support frame 54 for supporting the camera 53.
For taking an image of a transmission original such as a negative film, positive film or the like, an image input device requires transmission illumination for illuminating a transmission original from the back thereof.
In view of this, in the image input device shown in FIG. 10, there is provided a transmission illumination unit 52 placed on the original pedestal 51 with a power switch 55.
For taking an image of a transmission original such as a negative film, positive film or the like, a power source for the transmission illumination unit is required in addition to a power source for the image input device, resulting in a complicated structure.
Furthermore, since the transmission illumination unit is placed directly on the original pedestal, there is a possibility of forming scratches and stains on the original pedestal. Still further, since the transmission illumination unit is simply placed on the original pedestal without fixing the former to the latter, the transmission illumination unit might shift while taking an image on a film, resulting in poor operability.